Aluminum clad copper commutator for use with aluminum armature wire

ABSTRACT

A new and improved electrical commutator comprising a plurality of spaced apart plates wherein said plates have at least one outwardly projecting finger for holding an armature wire and wherein the plates are copper and the finger is copper integrally bonded to a side of aluminum.

o United States Patent 1151 3,668,449 King 1 June 6, 1972 541 ALUMINUMCLAD COPPER 3,244,917 4/1966 Gute ..310/237 x COMMUTATOR FOR USE WITH5g; 2/132; hariludge ....2391/ i/72233 1nter ALUMINUM ARMATURE vvIRE3,538,365 11/1970 Reisnecker. ..310/237 [72] Inventor: John B. King,Alton, 111. 3,478,421 1 H1969 Preece 210/237 X 2,436,910 3/1948 Werner..310/236 [73] Ass1gnee: 01in Corporation Primary Examiner-James D.Trammell [22] Flled Oct 1970 Assistant Examiner-Mark O. Budd [21] Appl.No.: 80,346 Attorney-Robert H. Bachman and Gordon G. Menzies [57]ABSTRACT [52] US. Cl ..3l0/236, 310/233, 29/597 [51] uuozk 13/04 A newand lmproved electncal commutator compnsmg a plurality of spaced apartplates wherein said plates have at least [58] Field of Search..310/233237, one outwardly projecting finger for holding an armaturewire 29/597 472'3 and wherein the plates are copper and the finger iscopper integrally bonded to a side of aluminum. [56] References CitedUNITED STATES PATENTS Parshall ..3l0/236 9 Claims, 5 Drawing FiguresPMENTEHJUH @1972 3,668,449

INVENTOR. JOHN B. KING BY fl a/W, I Z5 0 AGENT 1 ALUMINUM CLAD COPPERCOMMUTATOR FOR USE WITH ALUMINUM ARMATURE WIRE The present inventionrelates to a new and improved electrical commutator. More particularly,the present invention relates to a novel alloy composite havingincreased strength and weldability, as well as good formability andwearing characteristics.

At present many electrical devices such as commutators comprise co peror an alloy of solid copper, such as silver bearing oxygen free highconductivity copper, deoxidized low phosphorus copper, or low oxygensilver bearing copper.

The aforementioned materials are employed since in forming the hooks, orfingers, of the commutator severe deformation is required and thesematerials more easily deform without cracking since they are essentiallyfree of oxide strine Other properties which are important in thecommutator art however, in addition to electrical conductivity, areWearability, formability, weldability, and strength.

Wearability is important since the motor brushes ride on the commutatorsurface and thereby a commutator surface is required which will insuregood Wearability of the brushes. Also, since it is essential that thecommutator fingers do not break away during operation, suitable strengthcharacteristics are required of the material employed.

Naturally, also, the material to be employed must possess goodweldability since the fingers of the commutator are bent over and thenresistance welded to the magnet wire after winding of the armature.

The armature wire employed is of copper and is welded to the armature inorder to effect the required electrical connection.

It is known, however, that, aluminum has good electrical conductivityproperties but cannot be suitably employed as armature wire wherein thewire is welded to a copper commutator due to the formation ofdeleterious compounds at the weld temperature.

Further, an aluminum commutator has the disadvantage of causing rapidwearing of the brushes contacting the commutator due to the formation ofabrasive oxides of aluminum.

It is therefore desireable to provide a commutator wherein aluminumarmature wire may be advantageously employed with attendant costsavings.

It is therefore a principle object of the present invention to provide anew and improved commutator.

It is still a further object of the presentinvention to provide acommutator as aforesaid whereby the article is characterized by havingimproved weldability as well as good wearability and formability.

In accordance with the present invention, it has now been found that theforegoing objects and advantages may be readily obtained.

The present invention overcomes the disadvantages of the art and is asimple, convenient and highly useful article.

The present invention is an electrical commutator comprising a pluralityof spaced apart copper or high conductivity copper alloy plateselectrically insulated from each other wherein the plates have at leastone outwardly projecting finger for holding an armature wire, andfurther wherein the fingers are a composite comprising commercial purityaluminum, such as AA. 1 100 or E.C. grade aluminum, integrally bonded tocopper or a high conductivity copper alloy. The aforementioned platesare positioned about a suitable bushing, such as a plastic, with thealuminum component facing outwardly. Low Oxygen Electrolytic Tough PitchCopper, Electrolytic Tough Pitch Copper, or Oxygen Free HighConductivity Copper is the preferred copper.

The process of the present invention comprises integrally bonding copperor a high conductivity copper alloy, and preferably Low OxygenElectrolytic Tough Pitch Copper, Electrolytic Tough Pitch Copper, orOxygen Free High Conductivity Copper, to aluminum to form a compositesheet, forming fingers on an edge of the composite sheet, with thefingers parallel to the composite sheet and then forming the compositeinto a cylinder so that the aluminum is the outermost component. Thecylinder is then mounted about a bushing, the fingers bent so as tocatch and hold an armature wire, and the cylinder then broached betweenthe fingers to form a plurality of spaced apart plates. The aluminum isthen removed as for example by machining, from the outside surface ofthe cylinder which contacts the motor brushes.

F IG. 1 is a partial sectional view of the commutator before machining.

FIG. 2 is a perspective view of the commutator after bending of thefingers to catch and hold an armature wire.

FIG. 3 is a partial sectional view of the commutator after the finger iswound about with an armature wire.

FIG. 4 is a side view of the commutator after installation with thearmature, and machining away of the aluminum component upon which thebushes ride.

FIG. 5 is a partial sectional view of the commutator taken through line5-5 of FIG. 4.

Preferably, but not necessarily, the aforementioned bonding of thecomposite should be in accordance with the method of U5. Pat. No.3,381,366 which teaches convenient methods for producing composite metalarticles. For example, U.S. Pat. No. 3,381,366 teaches a method forpreparing an aluminum base alloy core composite. It is difficult toproduce a composite article having an aluminum core or cladding due tothe formation of both adherent and flaky oxides at moderate or elevatedtemperatures necessary for hot rolling. This oxide layer frequentlytends to break open during hot rolling but still can and often doescause severe problems. Briefly, the process described in theaforementioned US. Pat. No. 3,381,366 provides for heating the core of athickness less than 0.50 inch, to a temperature between 150 and l,050 Frolling together said core and cladding at a speed of at least 25 ft.per minute in one pass at a reduction range between 35 to percent withsaid core and cladding coming together for the first time in the bite ofthe rolls, said cladding of a thickness less than 0.250 inch andcontacting the roll prior to contacting of the core. It is necessarythat the included angle between the core and the cladding is in excessof 5 upon entering the rolls, with the preferred angle in excess of 10"An angle in excess of 10 will insure that the cladding and the core donot come together earlier than in the bite of the rolls.

Upon' entering the rolls, the cladding and the rolls are traveling atdifierent linear speeds whereas upon exiting from the rolls they aregoing at the same speed due to reduction in thickness of the composite.The difference in traveling speeds between the rolls and the cladding incombination with the precontacting of the cladding and the rollsgenerates a shear strain and introduces shearing at the bite of therolls and the core cladding interface. The shearing strain at thisinterface results in turbulent material flowthereby causing moreintimate bonding by increasing the interfacial linear surface of thecomposite by at least 20 percent. It is further noted that theinterfacial surface between the core and cladding is characterized bythe absence of interatomic diffusion, which may result in the formationof brittle compounds, between the core and cladding material.

Naturally, other methods of bonding may also be employed.

After forming the composite, an edge of the composite is blanked to formfingers extending parallel with respect to the composite sheet. Thecomposite is then further formed into a cylinder as, for example, byforming about a mandrel in a press, the cylinder is the mounted on asuitable bushing, and then the fingers are bent upwardly from thecylinder to catch and hold an armature wire. The cylinder is thenbroached between the fingers to form a plurality of spaced apart plates.Generally each plate has at least one finger, and normally a singlefinger.

, FIG. 1 shows the commutator 2 of the present invention after formingof the composite cylinder and before bending of the finger 4 intoposition to catch and hold an armature wire and machining away of thealuminum.

FIG. 2 shows the commutator 2 of the present invention after mounting ona bushing 6 before winding with the annature wire 8. The fingers 4 areshown in the-upright position after bending and circumferentially spacedapart to form hooks to catching and holding the armature wire duringwinding, as shown in FIG. 3.

During installation with an armature, after winding the wire aboutfinger 4 the finger is then further bent and welded to the magnet wireand the aluminum 10 machined away, as shown in FIG. 5.

The relatively high strength of the copper component 12 impartsincreased strength to the fingers of the commutator plates 14 of thecommutator 2. This is important since the high strength insures that thefingers 4 will not yield when the aramture 12 is wound, i.e., when thearmature wire 8 is hooked around the projecting fingers for shouldyielding occur the fingers 4 would require rebending; or failure maylater occur in service due to a poor joint where the fingers areresistance welded to the aluminum armature wire 8.

In addition weldability is very important since the fingers 4 of thecommutator must be welded to the armature wire 8 after theaforementioned winding and after they are bent over the wire, as shownin FIGS. 4 and 5.

Therefore, in accordance with the present invention the copper componentis a Low Oxygen Electrolytic Tough Pitch Copper of 99.90 percent minimumcopper and 0.02 percent oxygen maximum, or Electrolytic Tough PitchCopper of at least 99.90 percent copper and 0.04 nominal oxygen. OxygenFree High Conductive Copper of at least 99.95 percent copper may also bereadily employed.

The aluminum component may be any suitable grade of aluminum of therequired current carrying capacity, and is preferably AA. 1 100 aluminumof E.C. grade of at least 99.45 percent purity.

Generally, but not necessarily the thickness of the article afterbonding together to form a composite article and before theaforementioned machining ranges from 0.030 to 0.060 inches in thicknesswith the aluminum component comprising from about 5.0 to 20.0 percent ofthe thickness of the article, and preferably about 10.0 percent, withthe copper as the remainder.

The present invention is thus an electrical commutator having improvedweldability and strength as well as excellent machinability, formabilityand wear properties, and a method of producing the commutator.

The present invention will be more readily apparent from the followingillustrative example.

EXAMPLE E.C. grade aluminum was clad on one side of Low Oxygen ToughPitch Copper to form an integrally bonded composite. The composite wasthen cold rolled to about 0.050 inches then annealed to effectrecrystallization in both the aluminum and copper alloy components. Thefingers were then blanked out of an edge of the composite strip or sheetand the strip was then formed into a hollow commutator blank of 7/8 inchdiameter with a 5/16 inch contact surface. The blank was then filledwith a plastic and then tumbled to remove any excess plastic material.The fingers, each about three-sixteenths inch long as measured from itsbase when in the flat condition and characteristics thereof. The presentembodiment is therefore to be considered as in all respects illustrativeand not restrictive, the scope of the invention being indicated by theappended claims, and all changes which come within the meaning and rangeof equivalency are intended to be embraced therein.

What is claimed is:

1. An electrical commutator comprising: a plurality of plates mounted ina cylindrical fashion about a bushing, said plates being spaced apartand electrically insulated one from the other, said plates having meansfor bonding to an aluminum armature wire integral therewith comprisingat least one outwardly projecting finger from an edge of said plate,said plates comprising a material selected from the group consisting ofcopper and high conductivity copper alloys and said finger being acomposite comprising a base of said material integrally bonded to acladding of aluminum with said aluminum facing outwardly with respect tosaid bushing when said finger is substantially horizontal to the outsidesurface of said bushing before bending and welding of the finger to thearmature wire.

2. An electrical commutator in accordance with claim I wherein saidcopper is selected from the group consisting of L Oxygen ElectrolyticTough Pitch Copper, Electrolytic Tough Pitch Copper, and Oxygen FreeHigh Conductivity Copper.

3. An electrical commutator in accordance with claim 2 wherein saidaluminum is selected from the group consisting of A.A. l EC. gradealuminum.

4. An electrical commutator in accordance with claim 2 wherein saidfingers project towards the opposing edges of said plates andsubstantially parallel the faces thereof.

5. An electrical commutator in accordance with claim 4 further includingan armature wire positioned between said fingers and said faces andresistance welded to said fingers and said plates.

6. An electrical commutator in accordance with claim 2 wherein each ofsaid plates has a single outwardly extending finger.

7. An electrical commutator in accordance with claim 6 wherein saidcomposite is from 0.030 to 0.060 inches thick and wherein said aluminumand said plate is from 5 to 30 percent of the thickness and said finger.

8. An electrical commutator in accordance with claim 7 wherein saidaluminum is about 10 percent of the thickness of said finger.

9. An electrical commutator in accordance with claim 5 wherein saidcopper contains as impurities 0.2 maximum oxygen, 0.03 percent maximumzinc, total all other impurities less than 0.03 percent nominal.

UNITED STATES PATENT OFFIQE QERTIFICATE 0F CORRECTEQN pa 3,668,449 DatedJune 6, 1972 Inventor(s) John B. King It is certified that error appearsin the above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column .4, line 33, after "of insert Low Column 4, line 38, after "1100"insert and Signed and sealed this 3rd day of October 1972.

(SEAL) Attest:

EDWARD MGFLE TCHER ,JR ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-IOSO (10-69) USCOMM-DC 60376-P69 Q u.s. GOVERNMENTPRXNTING'OFFICE. I969 c-Jse-JJ-x UNITED STATES PATENT OFFIE (IERTIFICATE0F CORRECTEON Dated Jime 6, 1972 Patent No 8,449

Inventor(s) John B. King It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 4, line 33, after "of" insert Low Column 4, line 38, after "1100"insert and Signed and sealed this 3rd day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissionerof Patents USCQMM-DC 60376-P69 Q u.5. GOVERNMENT PRINTING OFFICE. 19690-366-3Jd FORM PC7-1050 (10-69)

2. An electrical commutator in accordance with claim 1 wherein saidcopper is selected from the group consisting of L Oxygen ElectrolyticTough Pitch Copper, Electrolytic Tough Pitch Copper, and Oxygen FreeHigh Conductivity Copper.
 3. An electrical commutator in accordance withclaim 2 wherein said aluminum is selected from the group consisting ofA.A. 1100 E.C. grade aluminum.
 4. An electrical commutator in accordancewith claim 2 wherein said fingers project towards the opposing edges ofsaid plates and substantially parallel the faces thereof.
 5. Anelectrical commutator in accordance with claim 4 further including anarmature wire positioned between said fingers and said faces andresistance welded to said fingers and said plates.
 6. An electricalcommutator in accordance with claim 2 wherein each of said plates has asingle outwardly extending finger.
 7. An electrical commutator inaccordance with claim 6 wherein said composite is from 0.030 to 0.060inches thick and wherein said aluminum and said plate is from 5 to 30percent of the thickness and said finger.
 8. An electrical commutator inaccordance with claim 7 wherein said aluminum is about 10 percent of thethickness of said finger.
 9. An electrical commutator in accordance withclaim 5 wherein said copper contains as impurities 0.2 maximum oxygen,0.03 percent maximum zinc, total all other impurities less than 0.03percent nominal.